Apparatus for drawing and crimping synthetic yarn

ABSTRACT

An apparatus is described for drawing synthetic yarn and rendering the yarn in condition for immediate crimping. The apparatus which is relatively compact, draws the yarn between a surface roughened draw pin and a heated roll. The yarn is heated to its drawing temperature by frictional contact with the draw pin surface. The apparatus produces an improved yarn in that a preheating stage is not required and the yarn is not permitted to shrink after drawing.

United States Patent [1 1 Bird [ Oct. 28, 1975 APPARATUS FOR DRAWING AND CRIMPING SYNTHETIC YARN [75] Inventor:

[73] Assignee: Dow Badische Canada Limited,

Ottawa, Canada [22] Filed: Jan. 14, 1974 [21] Appl. N0.: 432,925

David Owen Bird, Arnprior, Canada [52] US. C1 28/1.6; 28/71.3

[51] Int. CI. D02G l/l2; D02J 1/22 [58] Field of Search 28/71.3, 1.6; 264/290 R, 264/290 N [56] References Cited UNITED STATES PATENTS 2,767,429 10/1956 McCrosky 28/71.3

3,073,001 1/1963 Kroll 28/71 3 3,083,412 4/1963 Brignac et al... 264/290 N 3,154,807 11/1964 Muller et a1. 28/71.3

3,229,015 1/1966 Kramer 28/71.3 X

3,416,188 12/1968 Fukuma et a1 28/71.3 X 3,422,491 1/1969 Kihara et a1. 29/7l.3 X 3,436,450 4/1969 Specker et a1. 264/290 N X 3,561,045 2/1971 Heffernan 28/71.3 X 3,715,421 2/1973 Martin et aI. 28/71.3 X

FOREIGN PATENTS OR APPLICATIONS 46-11047 3/1971 Japan 264/290 R Primary ExaminerRobert R. Mackey [57] ABSTRACT An apparatus is described for drawing synthetic yarn and rendering the yarn in condition for immediate crimping. The apparatus which is relatively compact, draws the yarn between a surface roughened draw pin and a heated r011. The yarn is heated to its drawing temperature by frictional contact with the draw pin surface. The apparatus produces an improved yarn in that a preheating stage is not required and the yarn is not permitted to shrink after drawing.

3 Claims, 1 Drawing Figure US. Patent Oct. 28, 1975 APPARATUS FOR DRAWING AND CRIMPING SYNTHETIC YARN This invention relates to an apparatus for drawing synthetic textile yarn. More particularly, it relates to an apparatus for heat drawing synthetic yarn and rendering the yarn in condition for immediate crimping.

Synthetic yarn such as .polyamide is heat softened to its drawing temperature 'anddrawn to increase yarn strength prior to subjecting the yarn to a crimping operation. Apparatus for heatdrawing. yarn are known in the art. The nature of such apparatus usually requires a relatively long draw path which-necessitates the construction of an apparatus which takes up a large amount of space. When crimping is .desired in the yarn after drawing, drawn yarn produced on such prior art apparatus required a preheating operation before crimping. This not only required a cumbersome series of metering rolls and drive rolls in the apparatus but the preheating operation tended to damage the yarn by weakening its tensile strength or adversely effecting its dyeing characteristics should the yarn be one which had been modified to change its dye receptive characteristics in an earlier operation- The present apparatus which is designed to heat draw synthetic yarn such as nylon and render it in condition for immediate crimping is by the combination and positioning of its elements capable of producing drawn yarn which is less susceptible to damage during stretching and is itself generally cheaper to construct, being reduced to the most essential elements. It also takes up The single FIGURE of drawing shows the main elements of the apparatus in schematic form for purposes of illustration.

in the drawing, undrawn synthetic textile yarn I such as polyamide enters the apparatus from a cone of such yarn (not shown) or from a yarn production line and passes into the apparatus in the direction shown by the arrow. A variable pretension unit 2 is positioned immediately downstream of the entrance so that the yarn can enter the apparatus under slight tension to facilitate handling. This tension can be varied depending on the nature of the synthetic yarn itself. The yarn is then passed through motor driven metering rolls 3 which control the rate of passage of the yarn through the apparatus.

The yarn is led around draw pin 4 which is rigidly secured on the apparatus. This draw pin is made of a heat conductive material such as aluminum, steel or ceramic and has a hard roughened surface of a type to be described in more detail below. The yarn can be looped around pin 4 and for best results the yarn is looped around two or three times. As the yarn is passed over the roughened surface of pin 4 under tension, the friction between the yarn and the roughened surface causes the yarn to heat up. After a few minutes of warm-up operations it was found that the heat transfer between the yarn and the pin due to such friction was sufficient to raise the yarn to its draw temperature. The roughened surface of pin 4 must be within very critical dimensions. If the surface characteristics are outside these dimensions the yarn will either stick to the pin considerably less space than the apparatus of the prior 7 art due to the way these elements are positioned and the shorter draw path needed for this apparatus.

It is therefore an object of this invention to provide an improved apparatus for heat drawing synthetic textile yarn and rendering the yarn in condition for immediate crimping.

it is another object of this invention to provide an apparatus for producing an improved heat drawn yarn in condition for immediate crimping.

These objects are obtained by means of an apparatus which comprises:

a. means for delivering undrawn synthetic textile yarn between the nip of a pair of metering rolls and means for rotating said rolls; a

b. a rigidly secured draw pin positioned in the same plane and spaced fromv said metering rolls, said draw pin consisting of a heat conductive material having a metal oxide coating deposited thereon by meansof a detonation gun and providing a roughened surface on said pin'wherein the peaks of such surface have a centre line average of from 60 to 120 micro inches and said surface has a coefficient of friction of from'0.l5 to 0.30;

c. a heated roll having an internal heating means and positioned above said draw pin diagonal to the plane between the metering rolls and the draw pin;

d. means for rotating said heated roll'in a'direction opposite to the direction of rotation of said metering rolls and at a rate so as to draw a yarn extending between said draw pinand said heated roll to from three to'four times its undrawn length;

e. a separator roll spaced from said heated 'rolla'nd looped on said heated roll; and f. means for removing yarn from said heated roll.

adjacent thereto for'controlling the position of yarnsurface and eventually break due to the downstream tension on the yarn or, will pass over the pin without sufficient heat transfer.

The yarn is then passed from draw pin 4 to heated driven roll 5 and separator roll 6. It can be noted that when the yarn comes off pin 4 it changes its direction of travel by more than In the preferred construction of the apparatus this direction changes from to about In the prior art apparatus where heating of the yarn to its drawing temperature is done by means of heater rolls it is generally assumed that yarn drawing must be continued in the same direction as the yarn travels through such heater rolls for best results. This necessitated a long draw path and such apparatus took up a lot of space on the production floor. The applicant has found that by drawing from pin 4 which provides the draw temperature as well as one point of the draw path, the yarn can be changed in its direction of travel even to the extent of forming an acute angle with its original direction of travel off metering rolls 3. It is also noted that the applicants apparatus provides faster yarn drawing since better heat transfer is obtained by means of draw pin 4 than on conventional heater rolls.

The heated driven roll 5 is rotated at a faster rate than metering rolls 3 so that the yarn will be subjected to sufficient tension between draw pin 4 and roll 5 to draw the yarn. The speed of rotation of heated driven roll 5 can be varied depending on the degree of draw desired in the synthetic textile yarn 1. Roll 5 is motor driven and for purposes of simplicity is shown connected to motor driven metering rolls 3 by means of drive belt 9 so that both can be powered by a single motor unit. Roll 5 has a driving gear ratio which causes it to rotate faster than metering rolls 3, however, and of course rotates in the opposite direction to the rotation of metering rolls 3. The ratio of the rotational speed of roll 5 to metering rolls 3 is from about 3 to 1 up to 3 about 4 to 1 when the yarn is polyamide. The preferred running rate is 3.5 to l.

The yarn is passed over the heated driven roll 5 and separator roll 6 a number of times, usually from five to 20 loops provide the desired heating to render the yarn in condition for immediate crimping. When polyamide yarn was treated it was found that if roll 5 was heated to about 130C, the desirable conditioning took place. Roll 5 is heated by means of an initial electric element or other well known means and has a smooth conductive surface such as chrome steel. A drive belt 7 is shown connecting heated driven roll 5 with an electric motor 8. By means of the drive belt 7 the electric motor can rotate roll 5 at the desired rate. The drive belt 9 between roll 5 and metering rolls 3 can serve to drive the metering rolls 3 at a predetermined rate due to different gear ratios between roll 5 and rolls 3 as indicated previously so that the entire apparatus can be driven by motor 8 for the sake of simplicity.

Separator roll 6 is not heated and provides a means of keeping the loops of yarn on the heated roll 5 separated from each other as well as a means of guiding the loops along apredetermined path on the heated roll surface so that the entire length of yarn passes over substan tially the same temperature points on the surface of roll 5 and thereby receives substantially the same heat treatment. Furthermore the separator roll 6 prevents the loops on heated roll'S from touching each other and possibly sticking together.

As indicated previously the composition of draw pin 4 is critical to the smooth functioning of the apparatus. Thepin must be heat conductive and its surface must be roughened in a manner as to provide smooth running of the yarn over the pin surface while also providing sufficient friction to heat the yarn to its draw temperature. Roughening of the surface of the pin, which is usually made of aluminum, is" done by depositing a metal oxide 'coa'ting by means of a detonation gun. The preferred'co'ating'for this purpose is a composition con sisting of 60% aluminum oxide and 40% titanium dioxide and provided by Union Carbide under the trade name UCAR LA7. It was found that the peaks provided on' such surface should have a centre line average (CL'A) of from 60 to 120 micro inches. A preferred range is fr om '80 to 100 micro inches. In addition, in order to provide continuous running of the yarn on such surface it was found necessary that the surface have a coefficient of friction as measured on a Shirley frictometer of from 0. l 5 to 0.30 with a preferred range of from 0.21 'to 0.26.

The heated yarn from heated driven roll 5 is immediately passed to crimping unit 10 for crimping. Crimping unit 10 is a standard stuffer box crimper of the type well known'in the art.

Yarn 1 which enters the apparatus passes through metering rolls 3 which control the rate of passage of the yarn through the apparatus. The yarn passes around the pin and then off the pin in a direction about 125 to 135 from the yarn direction between metering rolls 3 and pin 4. In draw apparatus of the prior art, the yarn is preheated prior to drawing. This preheating tends to damage the yarn. For example, if the yarn has previously been modified to alter its dye receptive characteristics, such preheating tends to cause variations in the dye receptive characteristics through the yarn length and, of course, ultimately produces an unevenly dyed yarn.

4 In the present apparatus the yarn is drawn between pin 4 and heated driven roll 5. The yarn is heated by frictional contact with the pin 4 and is then immediately drawn. The yarn is not subjected to prolonged heating and is therefore less subject to heat damage.

The yarn is looped around heated driven roll 5 after drawing where it is heated to a temperature suitable for crimping. In the apparatus of the prior art, yarn is relatively cool after drawing and is either wound on spools forcrimping later or taken to a heating stage before crimping. When yarn is allowed to cool after drawing it tends to shrink slightly and therefore requires more crimps per inch to give suitable bulking. This additional crimping has a detrimental effect on the strength and appearance of the final product. In the applicants apparatus, the yarn is drawn between two heating elements. The pin 4 provides frictional heat sufficient to draw the yarn without damage. While the yarn cools somewhat on drawing, it is heated again by the heated driven roll 5 without giving the yarn a chance to shrink. This yarn can then be immediately subjected to a crimping operation.

The present apparatus was found to be particularly suitable for drawing polyamide yarn such as normal nylon and nylon which has been modified to alter its dye receptive characteristics. Some other forms of synthetic textile yarn can be processed as well.

I claim: I

1. An apparatus for drawing synthetic textile yarn and rendering said yarn in condition for immediate crimping, which comprises:

a. means for delivering undrawn synthetic textile yarn between the nip of a pair of metering rolls and means for rotating said rolls;

b. a rigidly secured draw pin positioned in the same plane and spaced from said metering rolls, said draw pin consisting of a heat conductive material having a metal oxide coating thereon and providing a roughened surface on said pin wherein the peaks of such surface have a centre line average of from 60 to 120 micro inches and said surface has a coefficient of friction of from 0.15 to 0.30, the friction generated between the yarn and draw pin being sufficient to raise the yarn to its draw temperature; a heated roll positioned above said draw pin diagonal to the plane between the metering rolls and the draw pin to render the yarn in condition for immediate crimping;

d. means for rotating said heated roll in a direction opposite to the direction of rotation of said metering rolls and at a rate so as to draw a yarn extending between said draw pin and said heated roll to from threeto four times its undrawn length;

e. a separator roll spaced from said heated roll and adjacent thereto for controlling the position of yarn looped on said heated roll; and

f. crimping means for removing yarn from said heated roll.

2. An apparatus as claimed in claim 1 wherein the metal oxide coating on said draw pin is a composition consisting of 60% aluminum oxide and 40% titanium dioxide. I g

3 An, apparatus as claimed in claim 1 wherein the peaks of the roughened surface on said draw pin have a centre line averageof from 80 to 100 micro inches and said surface has a coefficient of friction of from 

1. AN APPARATUS FOR DRAWING SYNTHETIC TEXTILE YARN AND RENDERING SAID YARN IN CONDITION FOR IMMEDIATE CRIMPING, WHICH COMPRISES: A. MEANS FOR DELIVERING UNDRAWN SYNTHETIC TEXTILE YARN BEBETWEEN THE NIP OF A PAIR OF METERING ROLLS AND MEANS FOR ROTATING SAID ROLLS, B. A RIGIDLY SECURED DRAW PIN POSITIONED IN THE SAME PLANE AND SPACED FROM SAID METERING ROLLS, SAID DRAW PIN CONSISTING OF A HEAT CONDUCTIVE MATERIAL HAVING A METAL OXIDE COATING THEREON AND PROVIDING A ROUGHENED SURFACE ON SAID PIN WHEREIN THE PEAKS OF SUCH SURFACE HAVE A CENTRE LINE AVERAGE OF FROM 60 TO 120 MICRO INCHES AND SAID SURFACE HAS A COEFFICIENT OF FRICTION OF FROM 0.15 TO 0.30, THE FRICTION GENERATED BETWEEN THE YARN AND DRAW PIN BEING SUFFICIENT TO RAISE THE YARN TO ITS DRAW TEMPERATURE, C. A HEATED ROLL POSITIONED ABOVE SAID DRAW PIN DIAGONAL TO THE PLANE BETWEEN THE METERING ROLLS AND THE DRAW PIN TO RENDER THE YARN IN CONDITION FOR IMMEDIATE CRIMPING, D. MEANS FOR ROTATING SAID HEATED ROOL IN A DIRECTION OPPOSITE TO THE DIRECTION OF ROTATION OF SAID METERING ROLLS AND AT A RATE SO AS TO DRAW A YARN EXTENDING BETWEEN SAID DRAW PIN AND SAID HEATED ROLL TO FROM THREE TO FOUR TIMES ITS UNDRAWN LENGTH,
 2. An apparatus as claimed in claim 1 wherein the metal oxide coating on said draw pin is a composition consisting of 60% aluminum oxide and 40% titanium dioxide.
 3. An apparatus as claimed in claim 1 wherein the peaks of the roughened surface on said draw pin have a centre line average of from 80 to 100 micro inches and said surface has a coefficient of friction of from 0.21 to 0.26. 